Tow dolly what do I need

I should add, last time I set a vehicle up for 4 down towing was my Dodge Dakota truck and I installed the baseplates myself. They weren't that difficult on a truck. I don't know how hard they are to install yourself on a car. The time before last I had a Jeep Cherokee. Just the install charges alone from the RV shop was something like $800 just to attach the baseplates. My local Jeep dealer had a body shop so I took it there. I showed them to the body guy and gave him the instructions and he installed them for $300. He had never done them before, but he was a regular body shop mechanic so was probably way more skilled than the workers at Camping World.